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Mol. Cells 2013; 36(1): 88-96

Published online June 4, 2013

https://doi.org/10.1007/s10059-013-0097-7

© The Korean Society for Molecular and Cellular Biology

Genetic Identification of a Second Site Modifier of ctr1-1 that Controls Ethylene-Responsive and Gravitropic Root Growth in Arabidopsis thaliana

Kihye Shin Rin-A Lee, Inhye Lee, Sumin Lee, Soon Ki Park, and Moon-Soo Soh

1Department of Molecular Biology, College of Life Science, Sejong University, Seoul 143-747, Korea, 2School of Applied Biosciences, Kyungpook National University, Daegu 702-701, Korea, 3These authors contributed equally to this work.

Received: March 26, 2013; Revised: May 2, 2013; Accepted: May 8, 2013

Abstract

Ethylene controls myriad aspects of plant growth throughout developmental stages in higher plants. It has been well established that ethylene-responsive growth entails extensive crosstalk with other plant hormones, particularly auxin. Here, we report a genetic mutation, named 1-aminocyclopropane carboxylic acid (ACC) resistant root1-1 (are1-1) in Arabidopsis thaliana (L.) Heynh. The CONSTITUTIVE TRIPLE RESPONSE1 (CTR1) encodes a Raf-related protein, functioning as an upstream negative regulator of ethylene signaling in Arabidopsis thaliana. We found that the ctr1-1, a kinase-inactive allele exhibited slightly, but significantly, longer root length, compared to ACC-treated wild-type or ctr1-3, a null allele. Our genetic studies unveiled the existence of are1-1 mutation in the ctr1-1 mutant, as a secondsite modifier which confers root-specific ethylene-resistance. Based on well-characterized crosstalk between ethylene and auxin during ethylene-responsive root growth, we performed various physiological analyses. Whereas are1-1 displayed normal sensitivity to synthetic auxins, it showed modest resistance to an auxin transport inhibitor, 1-Nnaphthylphthalamic acid. In addition, are1-1 mutant exhibited ectopically altered DR5:GUS activity upon ethylenetreatment. The results implicated the involvement of are1-1 in auxin-distribution, but not in auxin-biosynthesis, -uptake, or -sensitivity. In agreement, are1-1 mutant exhibited reduced gravitropic root growth and defective redistribution of DR5:GUS activity upon gravi-stimulation. Taken together with genetic and molecular analysis, our results suggest that ARE1 defines a novel locus to control ethylene-responsive root growth as well as gravitropic root growth presumably through auxin distribution in Arabidopsis thaliana.

Keywords Arabidopsis, auxin, ctr1-1, ethylene, gravitropism

Article

Research Article

Mol. Cells 2013; 36(1): 88-96

Published online July 31, 2013 https://doi.org/10.1007/s10059-013-0097-7

Copyright © The Korean Society for Molecular and Cellular Biology.

Genetic Identification of a Second Site Modifier of ctr1-1 that Controls Ethylene-Responsive and Gravitropic Root Growth in Arabidopsis thaliana

Kihye Shin Rin-A Lee, Inhye Lee, Sumin Lee, Soon Ki Park, and Moon-Soo Soh

1Department of Molecular Biology, College of Life Science, Sejong University, Seoul 143-747, Korea, 2School of Applied Biosciences, Kyungpook National University, Daegu 702-701, Korea, 3These authors contributed equally to this work.

Received: March 26, 2013; Revised: May 2, 2013; Accepted: May 8, 2013

Abstract

Ethylene controls myriad aspects of plant growth throughout developmental stages in higher plants. It has been well established that ethylene-responsive growth entails extensive crosstalk with other plant hormones, particularly auxin. Here, we report a genetic mutation, named 1-aminocyclopropane carboxylic acid (ACC) resistant root1-1 (are1-1) in Arabidopsis thaliana (L.) Heynh. The CONSTITUTIVE TRIPLE RESPONSE1 (CTR1) encodes a Raf-related protein, functioning as an upstream negative regulator of ethylene signaling in Arabidopsis thaliana. We found that the ctr1-1, a kinase-inactive allele exhibited slightly, but significantly, longer root length, compared to ACC-treated wild-type or ctr1-3, a null allele. Our genetic studies unveiled the existence of are1-1 mutation in the ctr1-1 mutant, as a secondsite modifier which confers root-specific ethylene-resistance. Based on well-characterized crosstalk between ethylene and auxin during ethylene-responsive root growth, we performed various physiological analyses. Whereas are1-1 displayed normal sensitivity to synthetic auxins, it showed modest resistance to an auxin transport inhibitor, 1-Nnaphthylphthalamic acid. In addition, are1-1 mutant exhibited ectopically altered DR5:GUS activity upon ethylenetreatment. The results implicated the involvement of are1-1 in auxin-distribution, but not in auxin-biosynthesis, -uptake, or -sensitivity. In agreement, are1-1 mutant exhibited reduced gravitropic root growth and defective redistribution of DR5:GUS activity upon gravi-stimulation. Taken together with genetic and molecular analysis, our results suggest that ARE1 defines a novel locus to control ethylene-responsive root growth as well as gravitropic root growth presumably through auxin distribution in Arabidopsis thaliana.

Keywords: Arabidopsis, auxin, ctr1-1, ethylene, gravitropism

Mol. Cells
May 31, 2023 Vol.46 No.5, pp. 259~328
COVER PICTURE
The alpha-helices in the lamin filaments are depicted as coils, with different subdomains distinguished by various colors. Coil 1a is represented by magenta, coil 1b by yellow, L2 by green, coil 2a by white, coil 2b by brown, stutter by cyan, coil 2c by dark blue, and the lamin Ig-like domain by grey. In the background, cells are displayed, with the cytosol depicted in green and the nucleus in blue (Ahn et al., pp. 309-318).

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